Platelet antibody analysis by three different tests

BACKGROUND

Platelet-reactive antibodies lead to thrombocytopenia and bleeding disorders, and diverse assays are used for their detection. In this retrospective analysis, the applicability of three different test systems was compared and antibody specificities were assessed.

METHODS

Sera of 1,234 patients were tested with an enzyme-linked immunosorbent assay (ELISA; Lifecodes PAKPLUS(®) or PAK 12(®), Gen-Probe) and a solid-phase assay (Capture-P Ready Screen(®), Immucor Inc.). In cases of suspected anti-HLA class I antibodies, a specific lymphocytotoxicity test (LCT, Bio-Rad(®)) was performed.

RESULTS

Platelet antibodies were detected in 366 of 1,234 samples (29.7%). In 70.3% concordant negative but only in 8.4% concordant positive results were obtained with both the methods; 185 of 1,053 in the solid-phase assay negative samples were positive in the ELISA (15.0%). In samples positive in both methods, most antibodies reacted against HLA class I antigens. Glycoprotein (GP) specific platelet antibodies, mainly against GPIIb/IIIa and GPIa/IIa, were more frequently detectable in the ELISA than in the solid-phase assay, whereas weakly positive results have to be interpreted cautiously.

CONCLUSION

ELISA, solid-phase assay, and LCT showed highly divergent results. Due to several limitations, the additional analysis by the "monoclonal antibody-specific immobilization of platelet antigen" (MAIPA)-assay is highly recommended.

Patatin-like phospholipase domain-containing protein 3 rs738409-G in recipients of liver transplants is a risk factor for graft steatosis

BACKGROUND & AIMS

The G-allele in position rs738409 of patatin-like phospholipase domain-containing protein 3 (PNPLA3) is associated with an increased hepatic concentration of triglyceride and is a risk factor for advanced liver disease. We investigated the association of donor and recipient risk alleles with the development of graft steatosis after liver transplantation.

METHODS

PNPLA3 genotypes were determined in 237 transplant recipients and in 255 organ donors. Macrovesicular steatosis was assessed by unenhanced computed tomography 5 years after liver transplantation in 95 patients and correlated with donor and recipient PNPLA3 genotype.

RESULTS

The risk allele was significantly more frequent in transplant recipients than in donors (42% vs 28%; P < .001). A prevalence of graft steatosis of 30% or greater significantly increased from 11.6% at 1 year after liver transplantation to 32.6% at 5 years after transplantation. Five years after liver transplantation, steatosis was present in 63.2% of patients homozygous for the rs738409-G allele, in 31.4% of heterozygous recipients, and in 12.0% of rs738409-CC recipients (P = .002). Donor genotypes were not associated with the development of graft steatosis. In multivariate regression analysis, recipients who carried rs738409-GG had a 13.7-fold higher risk of graft steatosis than recipients who carried rs738409-CC (P = .022), independent of recipient age, weight gain after liver transplantation, or the underlying disease.

CONCLUSIONS

Liver transplant recipients who carry rs738409-G in PNPLA3 are at increased risk for hepatic triglyceride accumulation, independent of the graft PNPLA3 genotype.

Nano-sized and micro-sized polystyrene particles affect phagocyte function

Adverse effect of nanoparticles may include impairment of phagocyte function. To identify the effect of nanoparticle size on uptake, cytotoxicity, chemotaxis, cytokine secretion, phagocytosis, oxidative burst, nitric oxide production and myeloperoxidase release, leukocytes isolated from human peripheral blood, monocytes and macrophages were studied. Carboxyl polystyrene (CPS) particles in sizes between 20 and 1,000 nm served as model particles. Twenty nanometers CPS particles were taken up passively, while larger CPS particles entered cells actively and passively. Twenty nanometers CPS were cytotoxic to all phagocytes, ≥500 nm CPS particles only to macrophages. Twenty nanometers CPS particles stimulated IL-8 secretion in human monocytes and induced oxidative burst in monocytes. Five hundred nanometers and 1,000 nm CPS particles stimulated IL-6 and IL-8 secretion in monocytes and macrophages, chemotaxis towards a chemotactic stimulus of monocytes and phagocytosis of bacteria by macrophages and provoked an oxidative burst of granulocytes. At very high concentrations, CPS particles of 20 and 500 nm stimulated myeloperoxidase release of granulocytes and nitric oxide generation in macrophages. Cytotoxic effect could contribute to some of the observed effects. In the absence of cytotoxicity, 500 and 1,000 nm CPS particles appear to influence phagocyte function to a greater extent than particles in other sizes.

Detection of a new HLA-A allele, designated HLA-A*32:53

The novel allele A*32:53 differs from A*32:01 by a single nucleotide substitution in exon 4 (position 649G>A).

Impact of constant storage temperatures and multiple warming cycles on the quality of stored red blood cells

BACKGROUND

Red blood cells (RBCs) are routinely stored in liquid state at temperatures below 6°C, and RBC unit core temperature should not exceed 10°C during transport. Since the critical temperature of 10°C was chosen mostly arbitrarily, this study investigated the effect of both constant temperature settings as well as multiple rewarming cycles on stored RBCs with respect to morphology, biochemical parameters and haemolysis.

MATERIALS AND METHODS

Buffy coat-depleted filtered RBCs were used as standard products. RBCs were stored at 1-6°C (reference group, n = 12), 13 and 22°C (test groups, n = 12 each) or stored at 1-6°C and warmed up five times to 10, 13, or 22°C for a period of 24 h each. Various biochemical parameters were measured weekly. RBCs were further investigated using electron microscopy.

RESULTS

Red blood cells stored constantly at 13 or 22°C showed stable haemolysis rates until day 28 and day 14, respectively. RBCs stored at 1-6°C with five warming-up periods to 10, 13 or 22°C each lasting 24 h (total 120 h) did not exceed the limit of the haemolysis rate at the end of storage. Differently shaped erythrocytes were found in all samples, but more crenate erythrocytes appeared after 42 days of storage independent of temperature profiles.

CONCLUSION

Red cells can be kept at constant temperatures above 6°C without apparent harmful effects at least until day 14, whereas multiple warming cycles for no longer than 24 h at 10, 13 or 22°C with subsequent cooling do not cause quality loss as assessed using the in vitro assays employed in this study.

Thermometry of red blood cell concentrate: magnetic resonance decoding warm up process

PURPOSE

Temperature is a key measure in human red blood cell concentrate (RBC) quality control. A precise description of transient temperature distributions in RBC units removed from steady storage exposed to ambient temperature is at present unknown. Magnetic resonance thermometry was employed to visualize and analyse RBC warm up processes, to describe time courses of RBC mean, surface and core temperatures by an analytical model, and to determine and investigate corresponding model parameters.

METHODS

Warm-up processes of 47 RBC units stored at 1-6°C and exposed to 21.25°C ambient temperature were investigated by proton resonance frequency thermometry. Temperature distributions were visualized and analysed with dedicated software allowing derivation of RBC mean, surface and core temperature-time courses during warm up. Time-dependence of mean temperature was assumed to fulfil a lumped capacitive model of heat transfer. Time courses of relative surface and core temperature changes to ambient temperature were similarly assumed to follow shifted exponential decays characterized by a time constant and a relative time shift, respectively.

RESULTS

The lumped capacitive model of heat transfer and shifted exponential decays described time-dependence of mean, surface and core temperatures close to perfect (mean R(2) were 0.999±0.001, 0.996±0.004 and 0.998±0.002, respectively). Mean time constants were τmean = 55.3±3.7 min, τsurface = 41.4±2.9 min and τcore = 76.8±7.1 min, mean relative time shifts were Δsurface = 0.07±0.02 and Δcore = 0.04±0.01. None of the constants correlated significantly with temperature differences between ambient and storage temperature.

CONCLUSION

Lumped capacitive model of heat transfer and shifted exponential decays represent simple analytical formulas to describe transient mean, surface and core temperatures of RBC during warm up, which might be a helpful tool in RBC temperature monitoring and quality control. Independence of constants on differences between ambient and storage temperature suggests validity of models for arbitrary storage and ambient temperatures.

Adverse events and safety issues in blood donation--a comprehensive review

Although blood donation is generally safe, a variety of risks and complications exist, the most common being iron deficiency, vasovagal reactions and citrate-related events. In the last decades, extensive efforts have significantly improved recipient and product safety, but there is still great potential to optimise donor care. Many therapies in modern medicine depend on the prompt availability of blood products, therefore it is crucial to maintain a motivated and healthy donor pool in view of a limited number of healthy volunteers willing and able to give blood or blood components. We present a comprehensive review on adverse events addressing all types of blood donation including whole blood, plasma, platelet, peripheral blood stem cell, leucocyte and bone marrow donation. In addition, we outline strategies for the prevention and treatment of these events and give a blueprint for future research in this field.

Pro-angiogenic induction of myeloid cells for therapeutic angiogenesis can induce mitogen-activated protein kinase p38-dependent foam cell formation

BACKGROUND AIMS

Clinical trials for therapeutic angiogenesis use blood- or bone marrow-derived hematopoietic cells, endothelial progenitor cells (EPC) and mesenchymal stromal cells (MSC) for vascular regeneration. Recently concerns have emerged that all three cell types could also contribute to atherosclerosis by foam cell formation. Therefore, we asked whether human myelomonocytic cells, EPC or MSC can accumulate lipid droplets (LD) and develop into foam cells.

METHODS

LD accumulation was quantified by flow cytometry, confocal microscopy and cholesterol measurement in each of the cell types. The impact of an initial pro-angiogenic induction on subsequent foam cell formation was studied to mimic relevant settings already used in clinical trials. The phosphorylation state of intracellular signaling molecules in response to the pro-angiogenic stimulation was determined to delineate the operative mechanisms and establish a basis for interventional strategies.

RESULTS

Foam cells were formed by monocytes but not by EPC or MSC after pro-angiogenic induction. Mitogen-activated protein kinase (MAPK) p38 phosphorylation was enhanced and kinase inhibition almost abrogated intracellular LD accumulation in monocytes.

CONCLUSIONS

These data suggest that hematopoietic cell preparations containing monocytes bear the risk of foam cell formation after pro-angiogenic induction. Instead, EPC and MSC may drive vascular regeneration without atherogenesis aggravation. A thorough understanding of cell biology is necessary to develop new strategies combining pro-angiogenic and anti-atherogenic effects during cell therapy.

Apheresis affects bone and mineral metabolism

BACKGROUND

Apheresis is a procedure to selectively obtain blood components. For the collection process citrate is routinely used. It inhibits coagulation by binding to ionized calcium and leads to metabolic alkalosis.

OBJECTIVE

Whether regular apheresis affects bone and mineral metabolism is unknown. The intention of this study was to investigate 1) the acute effects of apheresis on acid-base balance, bone and mineral metabolism and 2) to compare bone mineral density (BMD) at the lumbar spine and hip of donors to matched control subjects.

DESIGN

In this open, observational, single-center, cross-sectional study we enrolled 102 regular plasma and thrombocyte donors to pursue objective 1) and compared those to 102 matched controls (CTR) for objective 2).

RESULTS

Platelet donation led to significant decreases in serum ionized calcium (-17%) and phosphate (-18%), to marked increases in base excess (57%) and PTH levels (192%) during apheresis. Baseline biochemical comparisons between donors and CTR revealed significantly lower values for donors for serum calcium, albumin, and 25-hydroxyvitamin D levels. Mean Z-score at the lumbar spine adjusted for BMI, average physical activity and daily calcium intake was lower for donors (-0.28+/-0.11) when compared to CTR subjects (0.06+/-0.11, P<0.05). Total and neck femoral BMD was also lower in the donor group, however, this difference was not significant.

CONCLUSIONS

Exposure to citrate during the apheresis procedure acutely affects mineral and bone metabolism. Regular donations of blood components compromised BMD at the lumbar spine. If confirmed, strategies to prevent long-term effects on bone need to be formulated.

Identification of 14 new alleles at the fucosyltransferase 1, 2, and 3 loci in Styrian blood donors, Austria

BACKGROUND

Genes for fucosyltransferases 1 (FUT1:H), 2 (FUT2:Secretor), and 3 (FUT3:Lewis) encode enzymes crucial for ABH and Lewis blood group antigen synthesis. They are highly polymorphic and ethnically and geographically specific.

STUDY DESIGN AND METHODS

Genetic variations and allele frequencies of FUT1, FUT2, and FUT3 encoding regions and flanking sequences were analyzed in 100 Styrian blood donors by systematic sequencing. Haplotypes were verified with sequence-specific primers. To identify discrepancies, serologically determined ABO and Lewis blood groups were correlated to respective genotypes.

RESULTS

Two novel FUT1 alleles were defined by 9C>T (silent) and 991C>A (P331T) mutations, the latter located in the catalytic domain of the enzyme. Five new alleles of FUT2 were found: three were characterized by new variants and two resulted from new combinations of known polymorphisms. The new 412G>A (G138S) mutation also is located in the catalytic domain. A new nonsecretor allele, based on the presence of 428G>A (nonsense), was found. Another FUT2 allele may have resulted from an intragenic crossover event. FUT3 analysis revealed seven novel alleles, partly based on the new mutations 41G>A (R14H), 1060C>G (R354G), 735G>C (silent), and 882C>T (silent). While 41G>A is placed in the cytoplasmic domain and functional, 1060C>G is placed in the catalytic domain.

CONCLUSION

Multiple common and sporadic sequence variations including 14 new alleles at FUT1, FUT2, and FUT3 loci were identified. Four novel mutations result in amino acid substitution in the protein. Three of them are predicted to have adverse effects on the enzyme activity. A novel nonsecretor allele was found.

A new HLA-A*26 variant, A*2637 identified by haplotype-specific extraction and sequencing-based typing

The novel allele A*2637 differs from the common A*260101 by a single nucleotide substitution in exon 2 (position 186 C>G) causing an amino acid exchange (SER>ARG).

Rapid large-scale expansion of functional mesenchymal stem cells from unmanipulated bone marrow without animal serum

Adult mesenchymal stem cells (MSCs) are considered as valuable mediators for tissue regeneration and cellular therapy. This study was performed to develop conditions for regularly propagating a clinical quantity of > 2 x 10(8) MSCs without animal serum from small bone marrow (BM) aspiration volumes within short time. We established optimized culture conditions with pooled human platelet lysate (pHPL) replacing fetal bovine serum (FBS) for MSC propagation. MSC quality, identity, purity, and function were assessed accordingly. Biologic safety was determined by bacterial/fungal/mycoplasma/endotoxin testing and genomic stability by array comparative genomic hybridization (CGH). We demonstrate that unmanipulated BM can be used to efficiently initiate MSC cultures without the need for cell separation. Just diluting 1.5-5 mL heparinized BM per 500 mL minimum essential medium supplemented with L-glutamine, heparin, and 10% pHPL sufficiently supported the safe propagation of 7.8 +/- 1.5 x 10(8) MSCs within a single 11- to 16-day primary culture under defined conditions. This procedure also resulted in sustained MSC colony recovery. MSC purity, immune phenotype, and in vitro differentiation potential fully matched current criteria. Despite high proliferation rate, MSCs showed genomic stability in array CGH. This easy single-phase culture procedure can build the basis for standardized manufacturing of MSC-based therapeutics under animal serum-free conditions for dose-escalated cellular therapy and tissue engineering.

Thrombin generation before and after multicomponent blood collection

The development of apheresis technology has increased efficiency in donor blood use by collecting specific blood components in several combinations. The question of donor safety raised by the contact of donor blood with foreign, only in part biocompatible surfaces remains. The aim of this study was to estimate the effect of multicomponent blood collection on thrombin generation performing an overall function test of coagulation.

DONORS, METHODS

26 blood donors were included. Per apheresis two units of platelets and one unit of RBCs were collected by two cell separators (Amicus and Trima Accel). Each donor underwent the procedure on both apheresis systems. Samples were collected before, immediately after, and 48 hours after apheresis. Thrombin generation was measured by means of calibrated automated thrombography (CAT).

RESULTS

CAT-data changed only slightly and no significant changes were seen before, immediately after, and 48 hours after apheresis. The parameters did not differ significantly between the two different apheresis devices.

CONCLUSION

No change in parameters of continuous thrombin generation occurred, suggesting that apheresis did not lead to severe alterations in the haemostatic system.

Thrombin generation before and after multicomponent blood collection

BACKGROUND

Apheresis technology has made tremendous progress up to the development of automated blood component collection, which offers increased efficiency in donor blood use, but the concern about the contact of donor blood with artificial surfaces remains. Activation of the hemostatic system is a major issue in this context and is controversial. The aim of this study was to estimate the effect of apheresis on continuous thrombin generation (TG), representing a new tool to examine the overall function of the plasmatic clotting system.

STUDY DESIGN AND METHODS

Twenty-six voluntary blood donors, fulfilling the law requirement for apheresis donation, participated in the study. Two units of platelets (6 x 10(11)) and 1 unit of red cells (250 mL; hematocrit level, 80%) were collected using two types of cell separators (Amicus, Fenwal, Inc.; and Trima Accel, Gambro BCT). Each donor underwent collection on both apheresis systems with at least 8 weeks in between. Samples of blood were collected before, immediately after, and 48 hours after apheresis. TG was measured using a slow fluorogenic substrate by means of calibrated automated thrombography (CAT).

RESULTS

CAT data changed only slightly, and no significant changes were seen before, immediately after, and 48 hours after apheresis (p > 0.05). The variables did not differ significantly between the two different apheresis systems (p > 0.05).

CONCLUSION

Using a CAT-based technique, no change in variables of continuous TG were observed, suggesting that multicomponent blood collection did not lead to severe alterations in the hemostatic system of the donors.

Thrombin generation before and after multicomponent blood collection

IThe development of apheresis technology has increased efficiency in donor blood use by collecting specific blood components in several combinations. The question of donor safety raised by the contact of donor blood with foreign, only in part biocompatible surfaces remains. The aim of this study was to estimate the effect of multicomponent blood collection on thrombin generation performing an overall function test of coagulation. Donors, methods: 26 blood donors were included. Per apheresis two units of platelets and one unit of RBCs were collected by two cell separators (Amicus® and Trima Accel®). Each donor underwent the procedure on both apheresis systems. Samples were collected before, immediately after, and 48 hours after apheresis. Thrombin generation was measured by means of calibrated automated thrombography (CAT). Results: CATdata changed only slightly and no significant changes were seen before, immediately after, and 48 hours after apheresis. The parameters did not differ significantly between the two different apheresis devices. Conclusion: No change in parameters of continuous thrombin generation occurred, suggesting that apheresis did not lead to severe alterations in the haemostatic system.

Blood donor screening for parvovirus B19 in Germany and Austria

BACKGROUND

Although the main transmission pathway of parvovirus B19 (B19) is typically via the respiratory route, several transfusion-transmitted infections have been reported. To increase blood safety, all blood donations to our blood donor service have been screened by a B19 minipool real-time nucleic acid testing (NAT) since April 2000. Additional customers have been screened since the summer of 2003.

STUDY DESIGN AND METHODS

In total, 2.8 million donations from Germany and Austria were screened for B19 by real-time minipool NAT. A subgroup of 50 B19 DNA-positive donors was screened for B19 immunoglobulin G (IgG) and IgM antibodies and B19 DNA over a 6-month period. Results were compared to those of 100 B19 DNA-negative donors.

RESULTS

Data accumulated over the past 6 years indicate a high incidence period from May 2004 to January 2006. In total, the incidence was 12.7 and 261.5 per 100,000 donations with high virus loads equal to or above 10(5) and below 10(5) IU per mL, respectively. Median virus concentration in the case group was 4.85 x 10(7) IU per mL at Time Point T0 and was reduced to 4 x 10(2) IU per mL at the time of the next donation (3 months later). Neutralizing antibodies (VP2) were detected in all donations if virus load was reduced to less than 10(5) IU per mL.

CONCLUSION

The release of B19 DNA-positive blood products with a concentration of less than 105 IU per mL is thought to be safe due to the high level of neutralizing VP2 antibodies and is currently examined in a donor recipient infectivity study. In contrast, blood products with a high B19 DNA concentration (> or =10(5) IU/mL), some of which did not contain neutralizing antibodies, were discarded to protect at risk individuals.

A new HLA-B*44 variant, B*4453, identified by haplotype-specific extraction and sequencing-based typing

We report the identification of a novel HLA B*44 allele, officially named B*4453, found in an Austrian patient and his two sisters.

Human platelet lysate can replace fetal bovine serum for clinical-scale expansion of functional mesenchymal stromal cells

BACKGROUND

Human multipotent mesenchymal stromal cells (MSCs) are promising candidates for a growing spectrum of regenerative and immunomodulatory cellular therapies. Translation of auspicious experimental results into clinical applications has been limited by the dependence of MSC propagation from fetal bovine serum (FBS).

STUDY DESIGN AND METHODS

The capacity of human platelet lysate (HPL) to replace FBS for clinical-scale MSC propagation was analyzed.

RESULTS

HPL could be efficiently produced from buffy coats. Multiplex analyses allowed a distinct HPL growth factor profile to be delineated. With a previously established two-step clinical-scale procedure, HPL was reproducibly more efficient than FBS in supporting MSC outgrowth. With only 3 x 10(5) primary culture-derived MSCs, a mean of 4.36 x 10(8) HPL-MSCs (range, 3.01 x 10(8)-5.40 x 10(8)) was obtained within a single secondary 11- to 13-day culture step. Although morphologically distinct, HPL-MSCs and FBS-MSCs did not differ significantly in terms of immunophenotype, differentiation potential in vitro, and lack of tumorigenicity in nude mice in vivo.

CONCLUSIONS

Replacing FBS with HPL prevents bovine prion, viral, and zoonose contamination of the stem cell product. This new efficient FBS-free two-step procedure for clinical-scale MSC propagation may represent a major step toward challenging new stem cell therapies.

Two steps to functional mesenchymal stromal cells for clinical application

BACKGROUND

Ex vivo expansion of multipotent mesenchymal stromal cells (MSCs) is a prerequisite for evaluating their therapeutic potential in ongoing clinical trials. Even large volumes of starting material and extended culture periods, however, do not necessarily produce 2 x 10(6) MSCs per kg per adult patient. A new two-step procedure has been devised to propagate more than 1 x 10(8) MSCs from small marrow volumes within fewer than 4 weeks.

STUDY DESIGN AND METHODS

The influence of log fold decreased MSC seeding (2500, 250, 25, 2.5/cm(2)) on clinical-scale expansion, MSC phenotype, and immunomodulatory function combined with multiplex cytokine display was analyzed. Maintenance of MSC characteristics was tested in fibroblast colony-forming unit and differentiation assays.

RESULTS

Reduced seeding density boosted MSC propagation. Low-density expanded MSCs were CD29+, CD73+, CD90+, CD105+, CD14-, CD34-, CD45-, HLA-DR-; retained their differentiation potential; and inhibited lymphocyte proliferation. This was accompanied by deregulated cytokine production. Seeding 0.7 x 10(6) to 1 x 10(6) MSCs derived from a 10- to 13-day primary culture at a low density of 28 to 40 per cm(2) permitted propagation of 1.5 x 10(8) to 3.7 x 10(8) functional MSCs within a 13- to 15-day secondary expansion step.

CONCLUSION

Primary seeding of only 10-mL marrow aspirates on approximately 0.2-m(2) culture area (Step 1) followed by expansion on 2.5 m(2) (Step 2) is sufficient to consistently generate at least 1.5 x 10(8) MSCs in fetal bovine serum-supplemented medium within less than 4 weeks. The efficiency of this two-step procedure for clinical-scale MSC propagation may facilitate rational clinical testing of MSC-based therapies.

Humanized system to propagate cord blood-derived multipotent mesenchymal stromal cells for clinical application

Background: Umbilical cord blood (UCB) is an easily accessible alternative source for multipotent mesenchymal stromal cells (MSCs) and is generally believed to provide MSCs with a higher proliferative potential compared with adult bone marrow. Limitations in cell number and strict dependence of expansion procedures from selected lots of fetal bovine serum have hampered the progress of clinical applications with UCB-derived MSCs. Methods: We analyzed the isolation and proliferative potential of human UCB MSCs compared with bone marrow MSCs under optimized ex vivo culture conditions. We further investigated human platelet lysate as an alternative to replace fetal bovine serum for clinical-scale MSC expansion. Clonogenicity was determined in colony-forming units-fibroblast assays. MSC functions were tested in hematopoiesis support, vascular-like network formation and immune modulation potency assays. Results: MSCs could be propagated from UCB with and without fetal bovine serum. MSC propagation was effective in 46% of UCB samples. Once established, the proliferation kinetics of UCB MSCs did not differ significantly from that of bone marrow MSCs under optimized culture conditions, resulting in more than 50 population doublings after 15 weeks. A clinical quantity of 100 million MSCs with retained differentiation potential could be obtained from UCB MSCs within approximately 7 weeks. Ex vivo expansion of hematopoietic UCB-derived CD34+ cells as well as immune inhibition and vascular-like network formation could be shown for UCB MSCs propagated under both culture conditions. Conclusion: We demonstrate for the first time that human MSCs can be obtained and propagated to a clinical quantity from UCB in a completely bovine serum-free system. Surprisingly, our data argue against a generally superior proliferative potential of UCB MSCs. Functional data indicate the applicability of clinical-grade UCB MSCs propagated with human platelet lysate-conditioned medium for hematopoiesis support, immune regulation and vascular regeneration.

Immune cells mimic the morphology of endothelial progenitor colonies in vitro

Endothelial progenitor cells (EPC) are considered powerful biologic markers for vascular function and cardiovascular risk, predicting events and death from cardiovascular causes. Colony-forming units of endothelial progenitor cells (CFU-EC) are used to quantify EPC circulating in human peripheral blood. The mechanisms underlying colony formation and the nature of the contributing cells are not clear. We performed subtractive CFU-EC analyses to determine the impact of various blood cell types and kinetics of protein and gene expression during colony formation. We found that CFU-EC mainly comprise T cells and monocytes admixed with B cells and natural killer cells. The combination of purified T cells and monocytes formed CFU-EC structures. The lack of colonies after depletion or functional ablation of T cells or monocytes was contrasted with effective CFU-EC formation in the absence of CD34+ cells. Microarray analyses revealed activation of immune function-related biological processes without changes in angiogenesis-related processes during colony formation. In concordance with a regenerative function, soluble factors derived from CFU-EC cultures supported vascular network formation in vitro. Recognizing CFU-EC formation as the result of a functional cross between T cells and monocytes shifts expectations of vascular regenerative medicine. Our data support the move from a view of circulating EPC toward models that include a role for immune cells in vascular regeneration. Disclosure of potential conflicts of interest is found at the end of this article.

Immune reconstitution after purified autologous and allogeneic blood stem cell transplantation compared with unmanipulated bone marrow transplantation in children

Immune reconstitution is critical for the long-term success of haematopoietic stem cell transplantation (HSCT). We prospectively analysed immune reconstitution parameters after transplantation of autologous (group 1; n = 10) and allogeneic (group 2; n = 12) highly purified CD34+ peripheral blood stem cells (PBSC) and unmanipulated allogeneic bone marrow (BM) (group 3; n = 9) in children. Median follow-up after HSCT was 56 (group 1), 61 (group 2), and 40.5 months (group 3). Median CD34-cell dose transplanted in the three groups was 9.4 x 10(6)/kg, 20.3 x 10(6)/kg, and 4.25 x 10(6)/kg recipient's body weight (BW) respectively. Complete haematopoietic engraftment was seen in all patients without any significant differences between the three groups. T-cell reconstitution at 6 months was significantly delayed in autologous peripheral blood stem cell transplantation (PBSCT) compared with allogeneic BM transplantation (P < 0.028) and allogeneic PBSCT (P < 0.034). At 3 months after transplantation numbers of CD56+/3- natural killer cells were higher in the allogeneic PBSC group (P < 0.01) compared with the BM group. The numbers of proven bacterial and viral infections were equally distributed between the three groups. In conclusion, recipients of allogeneic highly purified CD34+ PBSC or unmanipulated BM have higher lymphocyte subset counts at 6 months after transplantation than recipients of autologous CD34-selected PBSC. Infection rates and outcome, however, were not significantly different.

Successful treatment of premature rupture of membranes after genetic amniocentesis by intra-amniotic injection of platelets and cryoprecipitate (amniopatch): a case report

BACKGROUND AND OBJECTIVES

Iatrogenic premature rupture of membranes (PROM) occurs in approximately 1% of patients after genetic amniocentesis. If membranes do not seal spontaneously, fluid leakage through the vagina may cause infection and pregnancy loss. Intra-amniotic infusion of a platelet concentrate followed by a cryoprecipitate (amniopatch) is a possible therapeutic approach to restore the amnio-corial link and to facilitate the amniotic repair process.

MATERIALS AND METHODS

The autologeous platelet concentrate was produced by apheresis (MCS+, Haemonetics) and contained a total amount of 48 x 10(9) platelets in a volume of 30 ml. The concentration of fibrinogen in our cryoprecipitate (20 ml) was 680 mg/dl. An amniocentesis was performed to apply the amniopatch. The platelet concentrate was administered first followed by the cryoprecipitate.

RESULTS

We report the successful treatment of a 38-year-old woman with ruptured membranes after genetic amniocentesis in the 16th gestational week. Ten days after placement of the amniopatch we found a complete closure of the rupture, and in the 36th week of gestation the patient delivered a healthy infant by Caesarean section.

CONCLUSIONS

Intra-amniotic injection of platelets and cryoprecipitate was a successful and safe therapy for PROM in this patient. Knowledge of the site of rupture is not necessary for the amniopatch, as platelets seem to find their way to the defect and seal it. We consider that amniopatch therapy for iatrogenic PROM is a possible therapeutic alternative for prolonging and preserving pregnancy and improving the fetal outcome.

Association between Chlamydia psittaci infection and extranodal marginal zone B-cell lymphoma of mucosa associated lymphoid tissue (MALT)-lymphomas

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Background: MALT-lymphomas are often associated with infectious organisms. Microbial species associated with MALT lymphomas are: Helicobacter pylori (H.pylori), Campylobacter jejuni, Borrelia burgdorferi, and Hepatitis C Virus. Recent studies showed evidence of Chlamydia psittaci (C. psittaci) infection in 80% of ocular adnexal lymphoma and tumor regression following eradication therapy. We studied the presence of C. trachomatis, C. pneumoniae, and C. psittaci DNAs in MALT lymphomas of various sites and in non-malignant controls. Methods: MALT lymphomas from the following sites were selected for analysis: salivary gland (n=13), thyroid gland (n=4), skin (n=2), ocular adnexa (n=2), stomach (n=6), intestinum (n=4). Samples of Sjoegren syndrome (n=10) and samples of H. pylori positive gastritis (n=7) were included as non-malignant controls. Macrodissected tissue containing >80% lymphoma cells from paraffin embedded tissue was processed for DNA isolation. For the presence of C. psittaci and C. pneumoniae DNA real time PCR assays were used. For C. trachomatis a commercially available PCR assay (Roche Molecular Diagnostics) was employed. All samples were tested twice. A sample was regarded as positive if at least one positive result was obtained. Results: C. psittaci was found at variable frequencies in MALT lymphomas of different sites: 4/13 (31%) salivary gland, 2/4 (50%) thyroid gland, 2/2 (100%) skin, 2/2 (100%) ocular adnexa, 1/6 (17%) gastric, and 0/4 intestinal MALT lymphomas. Among the non-malignant specimens, C. psittaci DNA was detected in 4/10 (40%) samples of Sjoegren syndrome and in 0/7 samples of H. pylori positive gastritis. All nongastric MALT lymphomas tested were negative for C. trachomatis and C. pneumoniae. Conclusion: Our data reveal a clear association of C. psittaci infection with extragastric MALT lymphoma. However, no evidence could be established for C. trachomatis and C. pneumoniae infection. Moreover, the high prevalence of Sjoegren syndromes - the most frequent precursor lesion for MALT lymphomas of salivary gland and ocular adnexa - may suggest an involvement of C. psittaci induced antigenic driven lymphomagenesis in a significant proportion of extragastric MALT lymphomas.

No significant financial relationships to disclose.

Severe thrombocytopenia due to host-derived anti-HPA-1a after non-myeloablative allogeneic haematopoietic stem cell transplantation for multiple myeloma: a case report

BACKGROUND AND OBJECTIVES

Host- or donor-derived alloimmune thrombocytopenia can develop after non-myeloablative allogeneic haematopoietic stem cell transplantation (HSCT). We report the first case of host-derived HPA-1a antibodies.

CASE REPORT

A 52-year-old male patient received HSCT from his human leucocyte antigen (HLA)-A, -B, -C, -DR identical brother after reduced intensity conditioning. Bilinear engraftment around day 12 was accompanied by a continuous decrease of platelet counts. We investigated for platelet antibodies because of a progressive decline of platelet counts and refractoriness to platelet transfusions.

METHODS

The patient's serum was tested by enzyme-linked immunosorbent assay (ELISA), a solid phase assay and monoclonal antibody-specific immobilization of platelet antigens (MAIPA) assay. Recipient's DNA from the time before HSCT and donor's DNA were genotyped for human platelet antigens.

RESULTS

Serum obtained on day 15 after HSCT reacted strongly with the donor's platelets due to host-derived anti-HPA-1a- and anti-HLA I antibodies. Serum samples from days 39, 45 and 65 after HSCT contained only anti-HLA I; no antibodies were detectable on day 149. Platelet counts increased on day 20 spontaneously. The decrease of the antibodies accompanied by the increase of the platelet counts suggests progressive elimination of residual host cells.

CONCLUSIONS

The HPA-1a antibodies affected thrombopoietic engraftment and the success of platelet transfusions.

Blood monocytes mimic endothelial progenitor cells

The generation of endothelial progenitor cells (EPCs) from blood monocytes has been propagated as a novel approach in the diagnosis and treatment of cardiovascular diseases. Low-density lipoprotein (LDL) uptake and lectin binding together with endothelial marker expression are commonly used to define these EPCs. Considerable controversy exists regarding their nature, in particular, because myelomonocytic cells share several properties with endothelial cells (ECs). This study was performed to elucidate whether the commonly used endothelial marker determination is sufficient to distinguish supposed EPCs from monocytes. We measured endothelial, hematopoietic, and progenitor cell marker expression of monocytes before and after angiogenic culture by fluorescence microscopy, flow cytometry, and real-time reverse transcription-polymerase chain reaction. The function of primary monocytes and monocyte-derived supposed EPCs was investigated during vascular network formation and EC colony-forming unit (CFU-EC) development. Monocytes cultured for 4 to 6 days under angiogenic conditions lost CD14/CD45 and displayed a commonly accepted EPC phenotype, including LDL uptake and lectin binding, CD31/CD105/CD144 reactivity, and formation of cord-like structures. Strikingly, primary monocytes already expressed most tested endothelial genes and proteins at even higher levels than their supposed EPC progeny. Neither fresh nor cultured monocytes formed vascular networks, but CFU-EC formation was strictly dependent on monocyte presence. LDL uptake, lectin binding, and CD31/CD105/CD144 expression are inherent features of monocytes, making them phenotypically indistinguishable from putative EPCs. Consequently, monocytes and their progeny can phenotypically mimic EPCs in various experimental models.

Anti-D immunization by DEL red blood cells

BACKGROUND

No data are available on the immunogenicity of extremely weak D variants called DEL. Evaluation of alloanti-D formation in a D- female patient after transfusion of apparently D- blood from an Austrian donor led to discovery of a so far unknown DEL type.

STUDY DESIGN AND METHODS

Standard blood group serologic methods were applied. Molecular typing, RHD sequencing, and D epitope mapping was performed and the absolute D antigen density determined.

RESULTS

After transfusion of RBCs typed D- by routine serology, the recipient developed alloanti-D. Further evaluation with an indirect antiglobulin test confirmed donor RBCs to be D-. Molecular typing, however, demonstrated the presence of the RHD gene in one donor, and RHD sequencing revealed a deletion of four nucleotides in RHD intron 5 (RHD IVS5-38del4) as the only difference compared to the normal RHD gene. Adsorption-elution techniques demonstrated a DEL phenotype without apparent loss of D epitopes.

CONCLUSION

This study documents the clinical significance of the DEL phenotype in blood units that was capable of inducing anti-D in a recipient. Qualitative data are provided on D epitope expression in DEL RBCs.

Tetragametic chimerism detected in a healthy woman with mixed-field agglutination reactions in ABO blood grouping

BACKGROUND

The case of a healthy woman with serologic blood group AB and her biologic father showing blood group O was investigated. Further analysis, including blood, buccal swabs, and nail clippings, revealed a tetragametic chimerism.

STUDY DESIGN AND METHODS

Blood grouping was performed with standard gel centrifugation test cards, ABO genotyping by sequence-specific primers (SSPs) and sequence-based typing, and HLA Class I and II typing by standard NIH cytotoxicity testing and SSP. Additionally, short-tandem-repeat (STR) and variable-number tandem-repeat (VNTR) typing was performed on blood, nail clippings, and buccal swab samples. The karyotype was analyzed by G-banded chromosomes.

RESULTS

The proposita's RBCs were typed AB with a mixed-field agglutination whereas in molecular typing A, B, and O alleles were found. One paternal and two maternal haplotypes were determined by use of HLA typing. Interestingly, both paternal alleles were detected in 4 of 23 tested STR and VNTR loci only, with whole blood, nail clippings, and buccal swabs. The karyotype was identified as 46XX. The family members including the proposita's healthy twin children displayed no abnormal findings in tests performed.

CONCLUSION

By investigation of DNA polymorphisms, it was possible to determine a rare case of tetragametic chimerism being the result of double parental contribution of nuclei.

Phenotypic characterization and preclinical production of human lineage-negative cells for regenerative stem cell therapy

BACKGROUND

Regenerative stem cell therapy (SCT) is currently being tested in clinical trials. The ideal type and source of cells have not yet been defined. Lineage (Lin) depletion is an experimental procedure capable of enriching all recently recognized SC types with regenerative potency. This study was performed to define a practicable monoclonal antibody (MoAb) cocktail for Lin depletion and to test whether clinical-scale Lin depletion is possible.

STUDY DESIGN AND METHODS

MoAbs (CD2/14/15/19/41/56/glycophorin A) were selected to mark seven mature hematopoietic lineages. Lin7-negative (Lin7NEG) cells were analyzed in peripheral blood (PB, n = 9), mobilized PB (MPB, n = 5), umbilical cord blood (UCB, n = 5), and marrow aspirates (BM, n = 4) by flow cytometry. Preclinical Lin depletion was tested with leukapheresis products from PB following good manufacturing practice (GMP) principles.

RESULTS

Lin7NEG cells comprised 0.23 +/- 0.04, 0.27 +/- 0.03, 0.53 +/- 0.07, and 0.49 +/- 0.03 percent of PB, MPB, UCB, and BM, respectively. Basophils, CD34+, and dendritic cells constituted the major Lin7NEG subpopulations (84 +/- 2, 90 +/- 3, 40 +/- 3, and 80 +/- 3% in PB, MPB, UCB, and BM, respectively). Minor populations included CD7- and CD45- cells. Preclinical CD2/14/15/19/56 (Lin5) depletion after automated red blood cell and platelet reduction resulted in up to a 16.7-fold enrichment of CD34+ and CD34-/Lin5NEG cells.

CONCLUSIONS

A seven-MoAb cocktail is sufficient to label more than 99 percent of nucleated cells in PB, MPB, UCB, and BM. Preclinical Lin depletion can be performed under GMP conditions from PB apheresis procedures.

Low propidium iodide intensity in flow cytometric white blood cell counting as a marker of cell destruction?

BACKGROUND

Residual white blood cells (WBC) in filtered blood products were investigated with flow cytometry. Frequently two distinct populations with different propidium iodide (PI) intensities can be found. The aim of this study was to specify a population with low PI intensity and discuss it as a marker of ongoing cell destruction and their possible impact on cytomegalovirus safety.

STUDY DESIGN AND METHODS

Buffy coat-depleted red blood cells were filtered with an in-line filtration set (LCR5, MacoPharma) after 4 hours (LCR5/4 hr) and 16 hours (LCR5/16 hr) of storage, and whole blood was filtered with a whole-blood filtration set (LST1, MacoPharma [LST1/4 hr]). The population with low PI intensity was sorted with a flow cytometer and prepared for transmission electron microscopy.

RESULTS

The absolute count obtained in the low-PI-intensity area before filtration was significantly different comparing LCR5/4 hr (11.5 x 10(6) +/- 6.84 x 10(6) and 0.12 x 10(6) +/- 0.1 x 10(6)/unit) and LCR5/16 hr (69.3 +/- 42.12 and 0.06 +/- 0.05; p < 0.002). By use of LST1/4 hr no difference was found compared to LCR5/4 hr after filtration (0.12 +/- 0.09 vs. 0.12 +/- 0.1), but a significant difference was found when comparing the results before filtration (1.25 +/- 0.41 vs. 11.5 +/- 6.84; p < 0.02). Electron microscopy revealed that the sorted population consisted of predominantly cell and nuclear fragments.

CONCLUSIONS

Events found in the low-PI-intensity area are not WBCs but partially degraded DNA coming from ongoing cell destruction during extended storage. Our results provide evidence that the absolute count of events found in the low-PI-intensity area can be used as a semiquantitative marker of WBC destruction.

Evaluation of a new enzyme-linked immunosorbent assay for the determination of neopterin

BACKGROUND

Determination of neopterin especially evaluated for use on the Behring ELISA Processor BEP III highly suited for the demands of blood donation screening in blood banks.

METHODS

A new commercially available enzyme-linked immunosorbent assay (ELISA) was developed for the detection of neopterin, a low-molecular-mass pteridine. Neopterin is produced by interferon-activated macrophages or monocytes during the activation of the cellular immune system in various diseases. In Austria testing of neopterin to detect cellular immune activation is mandatory since 1995. The former assay version has been used for the measurement of neopterin at the Medical University Graz. As a result of the cooperation with the blood bank in Graz and the Dade Behring company we have developed a new ELISA kit based on a special coating procedure. For comparison we performed measurements with the current IBL Neopterin ELISA version, the HPLC method and with the ELItest Neopterin ELISA (BRAHMS). The new assay is based on a simple assay procedure with two incubations of 1 h and of 30 minutes.

RESULTS

Linear regression analysis showed a significant correlation to the HPLC method. The assay is accurate and precise.

CONCLUSIONS

The above mentioned neopterin assay as an alternative method to other ELISA kits and the HPLC is highly suited for automation and was especially evaluated as a simple, rapid and reproducible version for the Behring ELISA Processor BEP III during this study.

Gender, age and seasonal effects on IgA deficiency: a study of 7293 Caucasians

BACKGROUND

The frequency of serum IgA deficiency (SIgAD) differs between populations. We examined the prevalence of SIgAD in healthy Caucasians.

MATERIALS AND METHODS

Serum immunoglobulin A (SIgA) was measured in 7293 volunteers (2264 women, 5029 men) aged 30 +/- 14.2 years (mean +/- SD; range: 12-66). Serum immunoglobulin A and subnormal SIgA levels were defined by a SIgA level < 0.07 g L(-1), and between 0.07 and 0.7 g L(-1), respectively. Means were compared by analysis of variance (anova) and analysis of covariance (ancova); frequencies by the chi(2) test.

RESULTS

Fifteen subjects (0.21%; one woman, 14 men) had SIgAD. Subnormal SIgA levels were found in 155 persons (2.13%): 21 females (0.93% of the females) and 134 males (2.66% of the males; difference: 1.74%; 95% CI: 1.12-2.33%; P < 0.001). Males were more likely to have subnormal SIgA levels or SIgAD (odds ratio 3.09, 95% CI: 1.97-4.85). The prevalence of SIgAD and subnormal SIgA was lowest in winter (chi(2) = 14.8; P = 0.002; 3 d.f.; and chi(2) = 43.2; P < 0.001; 3 d.f., respectively). Serum immunoglobulin A concentrations were significantly higher during winter. Serum immunoglobulin A levels increased with age on average by 0.2 +/- 0.06 g L(-1) per decade of life (P < 0.001). Taking into account the influence of age, SIgA concentration was lower in females as compared with males.

CONCLUSION

The prevalence of SIgAD and subnormal SIgA levels is increased in males. There exists a significant influence of gender, age and seasons on SIgA levels.

Pancytopenia due to suppressed hematopoiesis in a case of fatal hemolytic disease of the newborn associated with anti-K supported by molecular K1 typing

The authors report on a fatal case of hemolytic disease of the newborn (HDN) due to anti-K antibodies with subsequent trilineage pancytopenia in a preterm infant of 28 weeks gestational age, with pronounced leukopenia and neutropenia. In addition, molecular typing of the Kk polymorphism was necessary to confirm HDN. This case of HDN associated with anti-K provides additional evidence that trilineage pancytopenia due to suppressed hematopoiesis is part of the disease. Therefore, antibodies against antigens of the Kell blood group system should be considered as a potential cause of unexplained inhibition of myelopoiesis.

Ultrastructural changes and activation differences in platelet concentrates stored in plasma and additive solution

BACKGROUND

The aim of this study was to demonstrate how ultrastructural morphology of platelets stored in different media correlate with the appearance of particular activation markers on their cell surface.

STUDY DESIGN AND METHODS

Concentrates of buffy coat-derived platelets were stored in plasma or a glucose-free citrate-acetate-NaCl platelet additive solution (PAS2, Baxter Healthcare Corp.). Activation markers on platelets were measured by flow cytometry and compared with changes in the platelet cell surface as demonstrated by electron microscopy. Levels of the vasoactive cytokines vascular endothelial growth factor (VEGF) and RANTES (regulated upon activation, normal T-cell expressed and secreted) were determined in the storage medium of the platelet concentrate.

RESULTS

The activation markers CD62P and CD63 and the binding of thrombospondin measured by flow cytometry were expressed to a higher extent in the PAS2 group compared with the plasma group. The difference reached significance on Day 3 (CD62P: 66.37 +/- 2.44 vs. 37.83 +/- 2.03, p < 0.001; CD63: 42.11 +/- 3.29 vs. 34.84 +/- 2.04, p < 0.05; and thrombospondin binding: 18.84 +/- 3.9 vs. 13.98 +/- 3.87, p < 0.001, respectively). The form factor that is related to changes of the platelet shape was determined by image analysis and correlated significantly with the cell surface expression of CD62P (p < 0.001) and with CD63 (p < 0.05) and with thrombospondin binding (p < 0.05). The chemokines VEGF and RANTES were measured at higher levels in the PAS2 group.

CONCLUSIONS

With exception of baseline activation probably due to necessary handling procedures, platelets remain relatively unaltered and more stable in plasma in comparison to storage in PAS2.

Kell expression on myeloid progenitor cells

Kell is one of the major human red blood cell groups and comprises 22 antigens. These antigens are produced by alleles located on chromosome 7, including sets of antithetical antigens such as Kell (K, K1) and cellano (k, K2), which differ in a single amino acid change (T193M). It consists of a 93-Kd transmembrane glycoprotein that is surface-exposed and shares sequence and structural homology with zinc endopeptidases, which are involved in regulating bioactive peptides. Anti-Kell antibodies have been shown to suppress fetal erythropoiesis. Recently published data indicate a similar effect on myeolopoiesis and megakaryopoiesis. Substantial thrombocytopenia in fetuses affected with HDN due to anti-K antibodies led to the discovery of the inhibitory effect of Kell-related antibodies on CFU-MK growth. In addition to its inhibitory effect on BFU-E growth, anti-Kell antibodies significantly reduced CFU-GM colony formation from haematologically normal individuals. Moreover, anti-cellano and anti-Kp(b) antibodies also inhibited the growth of CFU-GM from antigen positive MNC. These data indicate that Kell is not restricted to erythroid blood cells, but is expressed on a broader spectrum of haematopoietic cells than previously believed.

Kinetics of CFU-Mk after automated plateletpheresis

BACKGROUND AND OBJECTIVES

Platelet count, thrombopoetin (TPO) level and the compartment of megakaryocyte progenitor cells (CFU-Mk) are major determinants in the regulation of thrombopoiesis. The aim of this study was to investigate the potential changes in the compartment of CFU-Mk and their correlation with serum TPO levels and platelet count after plateletpheresis.

MATERIALS AND METHODS

Twelve healthy individuals were randomly assigned to undergo single-donor plateletpheresis. A collagen-based in vitro culture system was used to determine the number of peripheral blood (PB) CFU-Mk before and after donation and on days 1, 4 and 7 thereafter. TPO levels were measured by a specific enzyme-linked immunosorbent assay and whole blood counts were performed using an automated cell counter.

RESULTS

The pre-apheresis platelet count (mean +/- SEM: 276 +/- 13 x 10(9)/l) decreased after plateletpheresis to a nadir of 194 +/- 8 x 10(9)/l (P < 0.001), showed a gradual increase on days 1 and 4, and reached pre-apheresis values by day 7 (280 +/- 11). The serum TPO levels were found to be significantly increased on days 1 and 7 as compared to baseline levels (baseline value 103.3 +/- 18.5 pg/ml versus day-1 value 135.8 +/- 25.8 pg/ml and day-7 value 132 +/- 30.19 pg/ml; P < 0.03 and P < 0.03, respectively). The numbers of CFU-Mk in PB were significantly elevated on day 4 only (125 +/- 21 colonies/ml of PB versus pre-apheresis values of 68 +/- 18 colonies/ml of PB, P < 0.005).

CONCLUSIONS

These findings suggest that platelet loss during plateletpheresis affects thrombopoiesis at the progenitor cell level, probably through alterations in TPO plasma concentrations.

IL-10 increases the number of CFU-GM generated by ex vivo expansion of unmanipulated human MNCs and selected CD34+ cells

BACKGROUND

Ex vivo expansion strategies with different cytokine combinations are currently used by several groups as a means of increasing the number of HPCs for a variety of special clinical applications. Because there is little information on the potential role of IL-10 in such ex vivo expansion models, the effect of this cytokine on the generation of myeloid progenitor cells in suspension cultures was investigated.

STUDY DESIGN AND METHODS

On the basis of data from the literature and from new experiments, the combination of SCF and IL-3 at concentrations of 100 ng per mL and 100 U per mL, respectively, was chosen as the standard cocktail. The addition of IL-10 to such cultures resulted in a marked and dose-dependent potentiation of myeloid progenitor cell production.

RESULTS

Using unmanipulated leukapheresis components from 13 individuals (including lymphoma and cancer patients and normal donors), the expansion multiple of CFU-GM after 14 days as compared with pre-expansion values was 9.54 +/- 2.31 times by SCF/IL-3 and 46.38 +/- 7.37 times by the combination of SCF/IL-3 and 100 ng per mL of IL-10 (p<0.001). IL-10 also potentiated CFU-GM generation from selected CD34 PBMNCs (n = 9) with an expansion of 17.22 +/- 7.04 times versus 45.67 +/- 16.78 times using the SCF/IL-3 and SCF/IL-3/IL-10 combination, respectively (p<0.05). Moreover, expansion-promoting effects of IL-10 were observed in liquid cultures containing MNCs from bone marrow (n = 4) and cord blood (n = 3), but did not reach statistical significance because of the small number of samples.

CONCLUSION

These results suggest IL-10 as a useful cytokine to optimize progenitor cell-expansion strategies for clinical application.